1. Field of the Invention
The present invention relates to a link tree forming method for setting individually selectable links for a plurality of objects displayed on a screen to form an overall object link tree.
2. Description of the Related Art
In general, a browser downloads HTML or similar contents from a server, and analyzes and displays those contents. By means of a keyboard, a mouse button, or a remote controller button, the user can shift the focus to, and select, a selectable item (Hyperlink, Object, etc.) within the displayed contents. Thus, when a browser is used on a machine that has a mouse, the user can make a selection simply by positioning the mouse pointer on the contents to be selected, and clicking a mouse button, but when a mouse is not used, as in the case of a WebTV, WebPAD or set-top box, operated only by means of a remote controller with a small number of buttons, or a portable terminal, etc., it is necessary for the browser to be capable of being fully operated with a limited number of buttons. With an apparatus that uses up/down buttons for one-dimensional move operations, link setting requires only the use of the array of selectable items (one-dimensional array) as is, but when cross-shaped move buttons (left, right, up, down) or the like are used for two-dimensional move operations, a two-dimensional move destination must be determined.
FIG. 23 is a flowchart showing a normal list tree formation procedure. When a Web Home Page is accessed, for example, contents are first downloaded from a URL (S700). The downloaded contents are analyzed, and laid out to enable them to be displayed by the browser (S701). From among the laid-out contents, a list of selectable items is created (S702), and finally a link tree of selectable items is created (S703).
In S703, basically a two-dimensionally selectable tree structure is created that makes it possible to focus on any selectable item by means of a move key operation. To be specific, an overall link tree is created by setting, for each selectable item, the next item as a right-direction link destination or a down-direction link destination in the one-dimensional list created in S702. In a one-dimensional list, selectable items are listed in order on the basis of the layout. Heretofore, links have been created simply with this list order as an absolute condition.
With this conventional method, there are many cases where it is not possible to move to the intended move destination, that is to say, what is visually the natural move destination. FIG. 24 shows an example of the result of link destination determination by the conventional method. In this drawing, selectable objects are numbered from 1 to 10, and those numbers constitute the list order. The origin of an arrow is a link source, and the end-point of an arrow is a link destination. In the drawing, visually it appears natural that (4) should be linked to (8) in a downward direction, but with the conventional method, (5), which appears earlier in the list, has priority as a link destination, and therefore (4) cannot be downward-linked to (8), but is downward-linked to (5). (There is a maximum of one link destination in one direction; a plurality of links cannot be created for one direction.) This linking method is unnatural for the user in visual terms, and the operation of a browser, etc., employing this kind of link setting is extremely user-unfriendly.